change one’s tune

(noun) a complete change of opinion or decision to the opposite

Example Sentences:

A: I heard you got accepted into Medical school. When do you start?
B: Actually, I changed my mind. I’m going to go to study Philosophy instead.
A: Why did you change your tune?

While researching Saudi Arabia for her vacation, Vanessa changed her tune and decided to go to Alaska instead.

Son: Dad, can we talk?
Dad: Sure.
Son: I’ve made a decision.
Dad: About what?
Son: I’m changing my tune, I don’t want to go to University. I’m going to travel to California instead.

From the Blogs:

The Nagging Harpy -- And, How To Change Her Tune

Media:

Similar idioms:

1. change of heart
2. about face
3. a leopard can’t change its spots
4. you can’t teach an old dog new tricks
5. change of pace
6. zone someone out
7. believe in
8. zone out
9. take a rain check
10. come through for someone
11. take a stand on
12. get through
13. sleep on it
14. on second thought